StdLib/LibC/gdtoa/strtodg.c

/** @file

  Copyright (c) 2012 - 2014, Intel Corporation. All rights reserved.<BR>
  This program and the accompanying materials are licensed and made available under
  the terms and conditions of the BSD License that accompanies this distribution.
  The full text of the license may be found at
  http://opensource.org/licenses/bsd-license.

  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

  *****************************************************************

  The author of this software is David M. Gay.

  Copyright (C) 1998-2001 by Lucent Technologies
  All Rights Reserved

  Permission to use, copy, modify, and distribute this software and
  its documentation for any purpose and without fee is hereby
  granted, provided that the above copyright notice appear in all
  copies and that both that the copyright notice and this
  permission notice and warranty disclaimer appear in supporting
  documentation, and that the name of Lucent or any of its entities
  not be used in advertising or publicity pertaining to
  distribution of the software without specific, written prior
  permission.

  LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
  IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
  SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
  IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
  ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
  THIS SOFTWARE.

  Please send bug reports to David M. Gay (dmg at acm dot org,
  with " at " changed at "@" and " dot " changed to ".").

  *****************************************************************

  NetBSD: strtodg.c,v 1.5.14.1 2008/04/08 21:10:55 jdc Exp
**/
#include  <LibConfig.h>

#include "gdtoaimp.h"

#ifdef USE_LOCALE
#include "locale.h"
#endif

#if defined(_MSC_VER)
  // Disable warnings about assignment within conditional expressions.
  #pragma warning ( disable : 4706 )
#endif

 static CONST int
fivesbits[] = {  0,  3,  5,  7, 10, 12, 14, 17, 19, 21,
    24, 26, 28, 31, 33, 35, 38, 40, 42, 45,
    47, 49, 52
#ifdef VAX
    , 54, 56
#endif
    };

 Bigint *
increment(Bigint *b)
{
  ULong *x, *xe;
  Bigint *b1;
#ifdef Pack_16
  ULong carry = 1, y;
#endif

  x = b->x;
  xe = x + b->wds;
#ifdef Pack_32
  do {
    if (*x < (ULong)0xffffffffL) {
      ++*x;
      return b;
      }
    *x++ = 0;
    } while(x < xe);
#else
  do {
    y = *x + carry;
    carry = y >> 16;
    *x++ = y & 0xffff;
    if (!carry)
      return b;
    } while(x < xe);
  if (carry)
#endif
  {
    if (b->wds >= b->maxwds) {
      b1 = Balloc(b->k+1);
      if (b1 == NULL)
        return NULL;
      Bcopy(b1,b);
      Bfree(b);
      b = b1;
      }
    b->x[b->wds++] = 1;
    }
  return b;
  }

 int
decrement(Bigint *b)
{
  ULong *x, *xe;
#ifdef Pack_16
  ULong borrow = 1, y;
#endif

  x = b->x;
  xe = x + b->wds;
#ifdef Pack_32
  do {
    if (*x) {
      --*x;
      break;
      }
    *x++ = 0xffffffffUL;
    }
    while(x < xe);
#else
  do {
    y = *x - borrow;
    borrow = (y & 0x10000) >> 16;
    *x++ = y & 0xffff;
    } while(borrow && x < xe);
#endif
  return STRTOG_Inexlo;
  }

 static int
all_on(CONST Bigint *b, int n)
{
  CONST ULong *x, *xe;

  x = b->x;
  xe = x + ((unsigned int)n >> kshift);
  while(x < xe)
    if ((*x++ & ALL_ON) != ALL_ON)
      return 0;
  if (n &= kmask)
    return ((*x | (ALL_ON << n)) & ALL_ON) == ALL_ON;
  return 1;
  }

 Bigint *
set_ones(Bigint *b, int n)
{
  int k;
  ULong *x, *xe;

  k = (unsigned int)(n + ((1 << kshift) - 1)) >> kshift;
  if (b->k < k) {
    Bfree(b);
    b = Balloc(k);
    if (b == NULL)
      return NULL;
    }
  k = (unsigned int)n >> kshift;
  if (n &= kmask)
    k++;
  b->wds = k;
  x = b->x;
  xe = x + k;
  while(x < xe)
    *x++ = ALL_ON;
  if (n)
    x[-1] >>= ULbits - n;
  return b;
  }

 static int
rvOK (
  double d, CONST FPI *fpi, Long *expt, ULong *bits, int exact, int rd, int *irv
)
{
  Bigint *b;
  ULong carry, inex, lostbits;
  int bdif, e, j, k, k1, nb, rv;

  carry = rv = 0;
  b = d2b(d, &e, &bdif);
  bdif -= nb = fpi->nbits;
  e += bdif;
  if (bdif <= 0) {
    if (exact)
      goto trunc;
    goto ret;
    }
  if (P == nb) {
    if (
#ifndef IMPRECISE_INEXACT
      exact &&
#endif
      fpi->rounding ==
#ifdef RND_PRODQUOT
          FPI_Round_near
#else
          Flt_Rounds
#endif
      ) goto trunc;
    goto ret;
    }
  switch(rd) {
    case 1:
    goto trunc;
    case 2:
    break;
    default: /* round near */
    k = bdif - 1;
    if (!k) {
      if (!exact)
        goto ret;
      if (b->x[0] & 2)
        break;
      goto trunc;
      }
    if (b->x[(unsigned int)k>>kshift] & ((ULong)1 << (k & kmask)))
      break;
    goto trunc;
    }
  /* "break" cases: round up 1 bit, then truncate; bdif > 0 */
  carry = 1;
 trunc:
  inex = lostbits = 0;
  if (bdif > 0) {
    if ( (lostbits = any_on(b, bdif)) !=0)
      inex = STRTOG_Inexlo;
    rshift(b, bdif);
    if (carry) {
      inex = STRTOG_Inexhi;
      b = increment(b);
      if ( (j = nb & kmask) !=0)
        j = ULbits - j;
      if (hi0bits(b->x[b->wds - 1]) != j) {
        if (!lostbits)
          lostbits = b->x[0] & 1;
        rshift(b, 1);
        e++;
        }
      }
    }
  else if (bdif < 0)
    b = lshift(b, -bdif);
  if (e < fpi->emin) {
    k = fpi->emin - e;
    e = fpi->emin;
    if (k > nb || fpi->sudden_underflow) {
      inex = b->wds = 0;
      *irv = STRTOG_Underflow | STRTOG_Inexlo;
      }
    else {
      k1 = k - 1;
      if (k1 > 0 && !lostbits)
        lostbits = any_on(b, k1);
      if (!lostbits && !exact)
        goto ret;
      lostbits |=
        carry = b->x[(unsigned int)k1>>kshift] &
                     (ULong)(1 << ((unsigned int)k1 & kmask));
      rshift(b, k);
      *irv = STRTOG_Denormal;
      if (carry) {
        b = increment(b);
        inex = STRTOG_Inexhi | STRTOG_Underflow;
        }
      else if (lostbits)
        inex = STRTOG_Inexlo | STRTOG_Underflow;
      }
    }
  else if (e > fpi->emax) {
    e = fpi->emax + 1;
    *irv = STRTOG_Infinite | STRTOG_Overflow | STRTOG_Inexhi;
#ifndef NO_ERRNO
    errno = ERANGE;
#endif
    inex = b->wds = 0;
    }
  *expt = e;
  copybits(bits, nb, b);
  *irv |= inex;
  rv = 1;
 ret:
  Bfree(b);
  return rv;
  }

 static int
mantbits(double d)
{
  ULong L;
  if ( (L = word1(d)) !=0)
    return P - lo0bits(&L);
  L = word0(d) | Exp_msk1;
  return P - 32 - lo0bits(&L);
  }

 int
strtodg (
  CONST char *s00, char **se, CONST FPI *fpi, Long *expt, ULong *bits
)
{
  int abe = 0, abits = 0, asub;
  int bb0, bb2, bb5, bbe, bd2, bd5, bbbits, bs2, c, decpt, denorm;
  int dsign, e, e1, e2, emin, esign, finished, i, inex, irv;
  int j, k, nbits, nd, nd0, nf, nz, nz0, rd, rvbits, rve, rve1, sign;
  int sudden_underflow = 0; /* pacify gcc */
  CONST char *s, *s0, *s1;
  double adj, adj0, rv, tol;
  Long L;
  ULong y, z;
  Bigint *ab, *bb, *bb1, *bd, *bd0, *bs, *delta, *rvb, *rvb0;

  e2 = 0; /* XXX gcc */

  irv = STRTOG_Zero;
  denorm = sign = nz0 = nz = 0;
  dval(rv) = 0.;
  rvb = 0;
  nbits = fpi->nbits;
  for(s = s00;;s++) switch(*s) {
    case '-':
      sign = 1;
      /* FALLTHROUGH */
    case '+':
      if (*++s)
        goto break2;
      /* FALLTHROUGH */
    case 0:
      sign = 0;
      irv = STRTOG_NoNumber;
      s = s00;
      goto ret;
    case '\t':
    case '\n':
    case '\v':
    case '\f':
    case '\r':
    case ' ':
      continue;
    default:
      goto break2;
    }
 break2:
  if (*s == '0') {
#ifndef NO_HEX_FP
    switch(s[1]) {
      case 'x':
      case 'X':
      irv = gethex(&s, fpi, expt, &rvb, sign);
      if (irv == STRTOG_NoNumber) {
        s = s00;
        sign = 0;
        }
      goto ret;
      }
#endif
    nz0 = 1;
    while(*++s == '0') ;
    if (!*s)
      goto ret;
    }
  sudden_underflow = fpi->sudden_underflow;
  s0 = s;
  y = z = 0;
  for(decpt = nd = nf = 0; (c = *s) >= '0' && c <= '9'; nd++, s++)
    if (nd < 9)
      y = 10*y + c - '0';
    else if (nd < 16)
      z = 10*z + c - '0';
  nd0 = nd;
#ifdef USE_LOCALE
  if (c == *localeconv()->decimal_point)
#else
  if (c == '.')
#endif
    {
    decpt = 1;
    c = *++s;
    if (!nd) {
      for(; c == '0'; c = *++s)
        nz++;
      if (c > '0' && c <= '9') {
        s0 = s;
        nf += nz;
        nz = 0;
        goto have_dig;
        }
      goto dig_done;
      }
    for(; c >= '0' && c <= '9'; c = *++s) {
 have_dig:
      nz++;
      if (c -= '0') {
        nf += nz;
        for(i = 1; i < nz; i++)
          if (nd++ < 9)
            y *= 10;
          else if (nd <= DBL_DIG + 1)
            z *= 10;
        if (nd++ < 9)
          y = 10*y + c;
        else if (nd <= DBL_DIG + 1)
          z = 10*z + c;
        nz = 0;
        }
      }
    }
 dig_done:
  e = 0;
  if (c == 'e' || c == 'E') {
    if (!nd && !nz && !nz0) {
      irv = STRTOG_NoNumber;
      s = s00;
      goto ret;
      }
    s00 = s;
    esign = 0;
    switch(c = *++s) {
      case '-':
        esign = 1;
        /* FALLTHROUGH */
      case '+':
        c = *++s;
      }
    if (c >= '0' && c <= '9') {
      while(c == '0')
        c = *++s;
      if (c > '0' && c <= '9') {
        L = c - '0';
        s1 = s;
        while((c = *++s) >= '0' && c <= '9')
          L = 10*L + c - '0';
        if (s - s1 > 8 || L > 19999)
          /* Avoid confusion from exponents
           * so large that e might overflow.
           */
          e = 19999; /* safe for 16 bit ints */
        else
          e = (int)L;
        if (esign)
          e = -e;
        }
      else
        e = 0;
      }
    else
      s = s00;
    }
  if (!nd) {
    if (!nz && !nz0) {
#ifdef INFNAN_CHECK
      /* Check for Nan and Infinity */
      if (!decpt)
       switch(c) {
        case 'i':
        case 'I':
        if (match(&s,"nf")) {
          --s;
          if (!match(&s,"inity"))
            ++s;
          irv = STRTOG_Infinite;
          goto infnanexp;
          }
        break;
        case 'n':
        case 'N':
        if (match(&s, "an")) {
          irv = STRTOG_NaN;
          *expt = fpi->emax + 1;
#ifndef No_Hex_NaN
          if (*s == '(') /*)*/
            irv = hexnan(&s, fpi, bits);
#endif
          goto infnanexp;
          }
        }
#endif /* INFNAN_CHECK */
      irv = STRTOG_NoNumber;
      s = s00;
      }
    goto ret;
    }

  irv = STRTOG_Normal;
  e1 = e -= nf;
  rd = 0;
  switch(fpi->rounding & 3) {
    case FPI_Round_up:
    rd = 2 - sign;
    break;
    case FPI_Round_zero:
    rd = 1;
    break;
    case FPI_Round_down:
    rd = 1 + sign;
    }

  /* Now we have nd0 digits, starting at s0, followed by a
   * decimal point, followed by nd-nd0 digits.  The number we're
   * after is the integer represented by those digits times
   * 10**e */

  if (!nd0)
    nd0 = nd;
  k = nd < DBL_DIG + 1 ? nd : DBL_DIG + 1;
  dval(rv) = (double)y;
  if (k > 9)
    dval(rv) = tens[k - 9] * dval(rv) + z;
  bd0 = 0;
  if (nbits <= P && nd <= DBL_DIG) {
    if (!e) {
      if (rvOK(dval(rv), fpi, expt, bits, 1, rd, &irv))
        goto ret;
      }
    else if (e > 0) {
      if (e <= Ten_pmax) {
        i = fivesbits[e] + mantbits(dval(rv)) <= P;
        /* rv = */ rounded_product(dval(rv), tens[e]);
        if (rvOK(dval(rv), fpi, expt, bits, i, rd, &irv))
          goto ret;
        e1 -= e;
        goto rv_notOK;
        }
      i = DBL_DIG - nd;
      if (e <= Ten_pmax + i) {
        /* A fancier test would sometimes let us do
         * this for larger i values.
         */
        e2 = e - i;
        e1 -= i;
        dval(rv) *= tens[i];
        /* rv = */ rounded_product(dval(rv), tens[e2]);
        if (rvOK(dval(rv), fpi, expt, bits, 0, rd, &irv))
          goto ret;
        e1 -= e2;
        }
      }
#ifndef Inaccurate_Divide
    else if (e >= -Ten_pmax) {
      /* rv = */ rounded_quotient(dval(rv), tens[-e]);
      if (rvOK(dval(rv), fpi, expt, bits, 0, rd, &irv))
        goto ret;
      e1 -= e;
      }
#endif
    }
 rv_notOK:
  e1 += nd - k;

  /* Get starting approximation = rv * 10**e1 */

  e2 = 0;
  if (e1 > 0) {
    if ( (i = e1 & 15) !=0)
      dval(rv) *= tens[i];
    if (e1 &= ~15) {
      e1 = (unsigned int)e1 >> 4;
      while(e1 >= (1 << (n_bigtens-1))) {
        e2 += (unsigned int)((word0(rv) & Exp_mask)
          >> Exp_shift1) - Bias;
        word0(rv) &= ~Exp_mask;
        word0(rv) |= Bias << Exp_shift1;
        dval(rv) *= bigtens[n_bigtens-1];
        e1 -= 1 << (n_bigtens-1);
        }
      e2 += (unsigned int)((word0(rv) & Exp_mask) >> Exp_shift1) - Bias;
      word0(rv) &= ~Exp_mask;
      word0(rv) |= Bias << Exp_shift1;
      for(j = 0; e1 > 0; j++, e1 = (unsigned int)e1 >> 1)
        if (e1 & 1)
          dval(rv) *= bigtens[j];
      }
    }
  else if (e1 < 0) {
    e1 = -e1;
    if ( (i = e1 & 15) !=0)
      dval(rv) /= tens[i];
    if (e1 &= ~15) {
      e1 = (unsigned int)e1 >> 4;
      while(e1 >= (1 << (n_bigtens-1))) {
        e2 += (unsigned int)((word0(rv) & Exp_mask)
          >> Exp_shift1) - Bias;
        word0(rv) &= ~Exp_mask;
        word0(rv) |= Bias << Exp_shift1;
        dval(rv) *= tinytens[n_bigtens-1];
        e1 -= 1 << (n_bigtens-1);
        }
      e2 += (unsigned int)((word0(rv) & Exp_mask) >> Exp_shift1) - Bias;
      word0(rv) &= ~Exp_mask;
      word0(rv) |= Bias << Exp_shift1;
      for(j = 0; e1 > 0; j++, e1 = (unsigned int)e1 >> 1)
        if (e1 & 1)
          dval(rv) *= tinytens[j];
      }
    }
  rvb = d2b(dval(rv), &rve, &rvbits); /* rv = rvb * 2^rve */
  if (rvb == NULL)
    return STRTOG_NoMemory;
  rve += e2;
  if ((j = rvbits - nbits) > 0) {
    rshift(rvb, j);
    rvbits = nbits;
    rve += j;
    }
  bb0 = 0;  /* trailing zero bits in rvb */
  e2 = rve + rvbits - nbits;
  if (e2 > fpi->emax + 1)
    goto huge;
  rve1 = rve + rvbits - nbits;
  if (e2 < (emin = fpi->emin)) {
    denorm = 1;
    j = rve - emin;
    if (j > 0) {
      rvb = lshift(rvb, j);
      rvbits += j;
      }
    else if (j < 0) {
      rvbits += j;
      if (rvbits <= 0) {
        if (rvbits < -1) {
 ufl:
          rvb->wds = 0;
          rvb->x[0] = 0;
          *expt = emin;
          irv = STRTOG_Underflow | STRTOG_Inexlo;
          goto ret;
          }
        rvb->x[0] = rvb->wds = rvbits = 1;
        }
      else
        rshift(rvb, -j);
      }
    rve = rve1 = emin;
    if (sudden_underflow && e2 + 1 < emin)
      goto ufl;
    }

  /* Now the hard part -- adjusting rv to the correct value.*/

  /* Put digits into bd: true value = bd * 10^e */

  bd0 = s2b(s0, nd0, nd, y);

  for(;;) {
    bd = Balloc(bd0->k);
    if (bd == NULL)
      return STRTOG_NoMemory;
    Bcopy(bd, bd0);
    bb = Balloc(rvb->k);
    if (bb == NULL)
      return STRTOG_NoMemory;
    Bcopy(bb, rvb);
    bbbits = rvbits - bb0;
    bbe = rve + bb0;
    bs = i2b(1);
    if (bs == NULL)
      return STRTOG_NoMemory;

    if (e >= 0) {
      bb2 = bb5 = 0;
      bd2 = bd5 = e;
      }
    else {
      bb2 = bb5 = -e;
      bd2 = bd5 = 0;
      }
    if (bbe >= 0)
      bb2 += bbe;
    else
      bd2 -= bbe;
    bs2 = bb2;
    j = nbits + 1 - bbbits;
    i = bbe + bbbits - nbits;
    if (i < emin) /* denormal */
      j += i - emin;
    bb2 += j;
    bd2 += j;
    i = bb2 < bd2 ? bb2 : bd2;
    if (i > bs2)
      i = bs2;
    if (i > 0) {
      bb2 -= i;
      bd2 -= i;
      bs2 -= i;
      }
    if (bb5 > 0) {
      bs = pow5mult(bs, bb5);
      if (bs == NULL)
        return STRTOG_NoMemory;
      bb1 = mult(bs, bb);
      if (bb1 == NULL)
        return STRTOG_NoMemory;
      Bfree(bb);
      bb = bb1;
      }
    bb2 -= bb0;
    if (bb2 > 0) {
      bb = lshift(bb, bb2);
      if (bb == NULL)
        return STRTOG_NoMemory;
      }
    else if (bb2 < 0)
      rshift(bb, -bb2);
    if (bd5 > 0) {
      bd = pow5mult(bd, bd5);
      if (bd == NULL)
        return STRTOG_NoMemory;
      }
    if (bd2 > 0) {
      bd = lshift(bd, bd2);
      if (bd == NULL)
        return STRTOG_NoMemory;
      }
    if (bs2 > 0) {
      bs = lshift(bs, bs2);
      if (bs == NULL)
        return STRTOG_NoMemory;
      }
    asub = 1;
    inex = STRTOG_Inexhi;
    delta = diff(bb, bd);
    if (delta == NULL)
      return STRTOG_NoMemory;
    if (delta->wds <= 1 && !delta->x[0])
      break;
    dsign = delta->sign;
    delta->sign = finished = 0;
    L = 0;
    i = cmp(delta, bs);
    if (rd && i <= 0) {
      irv = STRTOG_Normal;
      if ( (finished = dsign ^ (rd&1)) !=0) {
        if (dsign != 0) {
          irv |= STRTOG_Inexhi;
          goto adj1;
          }
        irv |= STRTOG_Inexlo;
        if (rve1 == emin)
          goto adj1;
        for(i = 0, j = nbits; j >= ULbits;
            i++, j -= ULbits) {
          if (rvb->x[i] & ALL_ON)
            goto adj1;
          }
        if (j > 1 && lo0bits(rvb->x + i) < j - 1)
          goto adj1;
        rve = rve1 - 1;
        rvb = set_ones(rvb, rvbits = nbits);
        if (rvb == NULL)
          return STRTOG_NoMemory;
        break;
        }
      irv |= dsign ? STRTOG_Inexlo : STRTOG_Inexhi;
      break;
      }
    if (i < 0) {
      /* Error is less than half an ulp -- check for
       * special case of mantissa a power of two.
       */
      irv = dsign
        ? STRTOG_Normal | STRTOG_Inexlo
        : STRTOG_Normal | STRTOG_Inexhi;
      if (dsign || bbbits > 1 || denorm || rve1 == emin)
        break;
      delta = lshift(delta,1);
      if (delta == NULL)
        return STRTOG_NoMemory;
      if (cmp(delta, bs) > 0) {
        irv = STRTOG_Normal | STRTOG_Inexlo;
        goto drop_down;
        }
      break;
      }
    if (i == 0) {
      /* exactly half-way between */
      if (dsign) {
        if (denorm && all_on(rvb, rvbits)) {
          /*boundary case -- increment exponent*/
          rvb->wds = 1;
          rvb->x[0] = 1;
          rve = emin + nbits - (rvbits = 1);
          irv = STRTOG_Normal | STRTOG_Inexhi;
          denorm = 0;
          break;
          }
        irv = STRTOG_Normal | STRTOG_Inexlo;
        }
      else if (bbbits == 1) {
        irv = STRTOG_Normal;
 drop_down:
        /* boundary case -- decrement exponent */
        if (rve1 == emin) {
          irv = STRTOG_Normal | STRTOG_Inexhi;
          if (rvb->wds == 1 && rvb->x[0] == 1)
            sudden_underflow = 1;
          break;
          }
        rve -= nbits;
        rvb = set_ones(rvb, rvbits = nbits);
        if (rvb == NULL)
          return STRTOG_NoMemory;
        break;
        }
      else
        irv = STRTOG_Normal | STRTOG_Inexhi;
      if ((bbbits < nbits && !denorm) || !(rvb->x[0] & 1))
        break;
      if (dsign) {
        rvb = increment(rvb);
        if (rvb == NULL)
          return STRTOG_NoMemory;
        if ( (j = rvbits & kmask) !=0)
          j = ULbits - j;
        if (hi0bits(rvb->x[(unsigned int)(rvb->wds - 1)
               >> kshift])
            != j)
          rvbits++;
        irv = STRTOG_Normal | STRTOG_Inexhi;
        }
      else {
        if (bbbits == 1)
          goto undfl;
        decrement(rvb);
        irv = STRTOG_Normal | STRTOG_Inexlo;
        }
      break;
      }
    if ((dval(adj) = ratio(delta, bs)) <= 2.) {
 adj1:
      inex = STRTOG_Inexlo;
      if (dsign) {
        asub = 0;
        inex = STRTOG_Inexhi;
        }
      else if (denorm && bbbits <= 1) {
 undfl:
        rvb->wds = 0;
        rve = emin;
        irv = STRTOG_Underflow | STRTOG_Inexlo;
        break;
        }
      adj0 = dval(adj) = 1.;
      }
    else {
      adj0 = dval(adj) *= 0.5;
      if (dsign) {
        asub = 0;
        inex = STRTOG_Inexlo;
        }
      if (dval(adj) < 2147483647.) {
        L = (Long)adj0;
        adj0 -= L;
        switch(rd) {
          case 0:
          if (adj0 >= .5)
            goto inc_L;
          break;
          case 1:
          if (asub && adj0 > 0.)
            goto inc_L;
          break;
          case 2:
          if (!asub && adj0 > 0.) {
inc_L:
            L++;
            inex = STRTOG_Inexact - inex;
            }
          }
        dval(adj) = (double)L;
        }
      }
    y = rve + rvbits;

    /* adj *= ulp(dval(rv)); */
    /* if (asub) rv -= adj; else rv += adj; */

    if (!denorm && rvbits < nbits) {
      rvb = lshift(rvb, j = nbits - rvbits);
      if (rvb == NULL)
        return STRTOG_NoMemory;
      rve -= j;
      rvbits = nbits;
      }
    ab = d2b(dval(adj), &abe, &abits);
    if (ab == NULL)
      return STRTOG_NoMemory;
    if (abe < 0)
      rshift(ab, -abe);
    else if (abe > 0)
      ab = lshift(ab, abe);
    rvb0 = rvb;
    if (asub) {
      /* rv -= adj; */
      j = hi0bits(rvb->x[rvb->wds-1]);
      rvb = diff(rvb, ab);
      if (rvb == NULL)
        return STRTOG_NoMemory;
      k = rvb0->wds - 1;
      if (denorm)
        /* do nothing */;
      else if (rvb->wds <= k
        || hi0bits( rvb->x[k]) >
           hi0bits(rvb0->x[k])) {
        /* unlikely; can only have lost 1 high bit */
        if (rve1 == emin) {
          --rvbits;
          denorm = 1;
          }
        else {
          rvb = lshift(rvb, 1);
          if (rvb == NULL)
            return STRTOG_NoMemory;
          --rve;
          --rve1;
          L = finished = 0;
          }
        }
      }
    else {
      rvb = sum(rvb, ab);
      if (rvb == NULL)
        return STRTOG_NoMemory;
      k = rvb->wds - 1;
      if (k >= rvb0->wds
       || hi0bits(rvb->x[k]) < hi0bits(rvb0->x[k])) {
        if (denorm) {
          if (++rvbits == nbits)
            denorm = 0;
          }
        else {
          rshift(rvb, 1);
          rve++;
          rve1++;
          L = 0;
          }
        }
      }
    Bfree(ab);
    Bfree(rvb0);
    if (finished)
      break;

    z = rve + rvbits;
    if (y == z && L) {
      /* Can we stop now? */
      tol = dval(adj) * 5e-16; /* > max rel error */
      dval(adj) = adj0 - .5;
      if (dval(adj) < -tol) {
        if (adj0 > tol) {
          irv |= inex;
          break;
          }
        }
      else if (dval(adj) > tol && adj0 < 1. - tol) {
        irv |= inex;
        break;
        }
      }
    bb0 = denorm ? 0 : trailz(rvb);
    Bfree(bb);
    Bfree(bd);
    Bfree(bs);
    Bfree(delta);
    }
  if (!denorm && (j = nbits - rvbits)) {
    if (j > 0)
      rvb = lshift(rvb, j);
    else
      rshift(rvb, -j);
    rve -= j;
    }
  *expt = rve;
  Bfree(bb);
  Bfree(bd);
  Bfree(bs);
  Bfree(bd0);
  Bfree(delta);
  if (rve > fpi->emax) {
 huge:
    rvb->wds = 0;
    irv = STRTOG_Infinite | STRTOG_Overflow | STRTOG_Inexhi;
#ifndef NO_ERRNO
    errno = ERANGE;
#endif
#ifdef INFNAN_CHECK
 infnanexp:
#endif
    *expt = fpi->emax + 1;
    }
 ret:
  if (denorm) {
    if (sudden_underflow) {
      rvb->wds = 0;
      irv = STRTOG_Underflow | STRTOG_Inexlo;
      }
    else  {
      irv = (irv & ~STRTOG_Retmask) |
        (rvb->wds > 0 ? STRTOG_Denormal : STRTOG_Zero);
      if (irv & STRTOG_Inexact)
        irv |= STRTOG_Underflow;
      }
    }
  if (se)
    *se = __UNCONST(s);
  if (sign)
    irv |= STRTOG_Neg;
  if (rvb) {
    copybits(bits, nbits, rvb);
    Bfree(rvb);
    }
  return irv;
  }